Having declared "war on pollution", China is arming itself with tougher weapons from new courts to daily fines and shutting down offenders altogether, in what analysts call promising steps but no guarantee of progress.

For decades, China accepted the blight on the environment as the collateral damage of tremendous economic growth that raised the incomes of hundreds of millions of people -- who now increasingly clamour for a better quality of life as well.

The acrid air, along with vast water and soil pollution, has not only afflicted the health and environment of the world's most populous country but also embarrassed the rising power as images of its capital smothered in smog scare off tourists and business.

In recent days levels of PM2.5, the smallest and most dangerous particulates, have at times been above 300 micrograms per cubic metre in Beijing, according to US embassy measurements -- 12 times the World Health Organization's recommended maximum level.

Yet powerful industries and local officials still eager to boost their bottom lines resist changing course.

At the same time, fixing the environment conflicts with the ruling Communist Party's overriding goal to grow the economy and improve livelihoods to avoid the "social unrest" that might shake its control.

"We can't say we're optimistic but we do see hopeful signs," said Ma Jun, a prominent Beijing-based environmentalist.

"We have seen some very concrete, very big action plans, which have some strong measures including public oversight."

But he added: "This implementation phase will be very difficult because it will touch on a lot of different interests, a lot of big investments."

- 'Genuine political will' -

Beijing has announced a series of pledges on the issue. At his annual press conference in March, Premier Li Keqiang declared "war on pollution", vowing to shut 50,000 small coal-fired furnaces and force six million older cars off the road.

The next month, the government updated its environmental protection law for the first time in 25 years to allow tougher penalties on polluters from next year, including daily fines, and for certain nonprofits to sue offenders.

In June, official media reported that 200 people were arrested last year for environmental offences and more than 3,500 businesses shut.

Last week, the Supreme Court announced the formation of a new tribunal to handle environmental cases.

But there are questions over how well the promises will be fulfilled.

The new tribunal's head Zheng Xuelin admitted that there were problems holding polluters to account, telling reporters: "Courts want to hear some cases but dare not to or become reluctant to do so due to certain interferences."

Nonetheless, Ma said the pledges represent a dramatic change from when the government refused to publish air quality data a few years ago. Now nearly 200 cities supply those figures.

"I think that regarding air pollution this is the first time the government has had the political will, genuine political will, to solve this problem," he said.

Water and soil pollution may come next, he added.

Sixty percent of China's underground water is too polluted to drink directly while a sixth of its land is polluted, official reports said this year, posing enormous though less obvious dangers including tainted food supplies.

- Overriding priorities -

China has previously set tough targets for air quality and promised to shave the proportion of energy generated from coal, a major pollution source, to 65 percent by 2017.

It pledged to spend 1,700 billion yuan ($270 billion) over five years to tackle air pollution, and to evaluate officials by how well they improved not only the economy but also air quality.

But already targets have been missed: air quality fell below national standards in all but three of 74 major cities last year.

Since taking over as head of the ruling party in late 2012, President Xi Jinping has assumed leadership of several committees covering security to economic growth -- but not the environment.

"I think this is a signal to say, maybe we talk a lot about this, but it's kind of symbolic," said Ran Ran, a professor at Renmin University.

The party leadership has repeatedly pledged to revamp slowing growth by encouraging Chinese to spend more -- but, she pointed out: "To stimulate domestic consumption definitely conflicts with environmental protection."

Meanwhile, allowing citizen watchdogs to hold polluters accountable could quickly bump up against the party's tendency to dictate the pace of reform.

Several prominent environmentalists -- notably Wu Lihong, who campaigned against pollution in Jiangsu province's Lake Tai, and Liu Futang, who spoke out against forest destruction on Hainan Island -- have been convicted in recent years.

Meanwhile, protests against chemical plants have been met with police crackdowns involving violence and arrests.

Governments such as China's "don't encourage public participation, have very low information flow (and) corruption with big industries", Ran said.

The new measures are "pointing in the right direction", said Alvin Lin, the China climate and energy policy director at the Natural Resources Defense Council.

"But actually making them effective, whether that actually changes behaviour by factories, by polluters, that's going to take longer."